Diamond truing device for profiling grinding disks with a grinding of helical singlecurve spur gears



March 21, 1961 J. LOOMAN ET AL 2,975,781

DIAMOND TRUING DEVICE FOR PROFILING GRINDING DISKS WITH A GRINDING OF HELICAL SINGLE CURVE SPUR GEARS Filed July 7, 1958 4 Sheets-Sheet 2 March 21, 1961` J. LOOMAN ETAL 2,975,731 DIAMOND TRUING DEVICE FOR PROFILING GRINDING DISKS WITH A GRINDING OF' HELICAL SINGLE CURVE SPUR GEARS 1958 4 Sheets-Sheet 3 Filed July 7,

March 21, 1961 J LOOMAN AL 2,975,781

DIAMOND TRUING DEVICE FOR PROFILING GRINDING DISKS WITH A GRINDING OF HELICAL SINGLE CURVE SPUR GEARS Filed July 7, 1958 4 Sheets-Sheet 4 to produce, the* desired` surface.

DIAMOND TRUING DEVICE FOR PROFILING GRINDING DISKSWITH A`GRINDING OF `HELICAL SINGLE CURVE SPUR GEARS Johannes Looman, Hermann Hofer, and Walter Thiemig, all` of Friedrichshafen (BodenseeLGermany, assrgnors to Zahnradfabrik Friedrichshafen Aktiengesellschaft,

' Friedrichshafen, Germany V Filed July 7, 1958, Ser. No. 746,896

Claims priority, application Germany July 5, 1957 17 Claims. (Cl. 125-11) This invention relates to diamond truing devices for profiling grinding wheels intendedto grind spur gear teeth erating line. Such devices have the frontal' involute path affected by jigs whereas the motion along the generating line is effected by means of a sliding bar inclined by a" predetermined 'angle, hereinafter referred to for the 'purposes of this invention as 13;, wherein control of the diamond movement is eflected by a pair of straight rods. In such a construction, the required jigs and the rods make for bulkiness and produce design difliculties.

In other types of devices a diamond dressing tool reproduces a tooth flank in the form of an involute helicoidal surface by means of a series of frontal involute the form ,of a diamond point carried by an element slidingly mounted on a plate providing for rolling motion, and sliding at an angle p relative a line running parallel to the axis of` the rolling cylinder. In such a device the surface'of the grinding disk is dressed by an enveloping series of outs effected by the dressing tool.

Accordingly, the object of the invention is to effect a dressing tool of the kind described which will be simple, rugged, and economical to manufacture and which will provide accurate results.

Another object of the invention is to provide a mechanism for dressing a grinding wheel in conjunction with a mechanism for holding and grinding a workpiece, that is, a gear, in such a way as to render convenient a shifting from dressing the grinding disk to grinding the workpiece. V

Other objects and features of the invention will appear in the detailed description to follow, taken in conjunction with the appended drawing in which:

Fig. 1 isa representation in perspective of a tooth of a helical single curve spur gear showing its generating line, with a contact line on the flank of the tooth and showing two involutes which circumscribe that part of the tooth flank occupied by the contact line.

Fig..2 is a representation of a perspective of the position of a dressing tool having an edge, as related to the generating line of the tooth shown in Fig. 1.

`Fig`. 3 is a representation in perspective showing a, single point dressing tool, such as a diamond point, which is movable along the tooth generating line.

'Fig. is a representation in perspective showing the 'mode of predetermining the motion of an edged dressing tool by means of a plate having a rolling contact on a fixed element of the circular configuration, to effect the motion schematically shown in Fig. 2.

Fig. 5 is a representation in perspective showing the mode' of predetermining the motion of a pointed dressing and spiral motions efieoting an envelope of grinding cuts I frontal involutes'are achieved by means of a plate `hav- 'In such devices, the a ing a rolling contact ,with a guide surface and the spirals are achieved by. connection of `'a rotatively mounted roller means 'to the screwdrive of the head stock of the machine. 'In such machines, the dressing diamond is firmly mounted on a plate having a rolling guide arrangement. It has' been found that such devices are not accurate and are subject to certain other disadvantages.

The; present invention seeks to overcome the faults of the prior devices generally described hereinabove by providing a dressing tool for truing a grinding wheel to :a desired profile wherein 'control of the tool depends on a plate having a rolling contact with a cylinder which is parallel to the workpiece axis, the rolling cylinder being fixed to the 'grinding machine. The dressing tool is disposed on the rolling-plate for cutting at the helix 'angle B of a helicoidal toothfiank.

One formof the invention provides for a' dressing. tool of conventional form having a straight cutting edge,

ln another form of the invention, the tr'uing tool takes' 'and a grinding wheel in conjunction with a workpiece to and B. The plane A contains an involute a--a', while tool, such as a diamond point, by means of a plate having a rolling contact and certain other elements to effect the motion shown diagrammatically in Fig. 3.

Fig. 6 shows a plan view of a device for controlling the uliotion of a dressing diamond in dressing a grinding wh'ee Fig. 7 is an elevation of the device shown in Fig'. 6.

Fig. 8 is an elevation showing schematically the operating position of a dressing tool, such as a diamond point,

be ground by the wheel, all as part of the same machine; and

Fig. 8a shows a diamond point dressing device of an- I other type, Which could be adapted to be mounted above the grinding wheel.

Referring now to Fig. 1, a cylinder 1 having the radius r of the base circle of a helical spur gear is shown. The cylinder axis is shown as the line 2, the circular ends of the cylinder being represented as planar frontal areas A the plane B contains the involute b`--b'. Such involutes, of course, represent the ends of a helical spur tooth having the helical flank 3. The flank is generated on the V hypotenuse line 4 of a right angle triangle 4--4'-4", developed from the base cylinder 1, wherein the line 4" constitutes an element of the surface of revolution of the cylinder. The edge 4 may be considered the gear generating line and will be understood to be at all times tangential to the helical line which contains the points t a-b--c--d, constituting the base line of the tooth and lying on the base circle cylinder 1. Thus, the line 4 always crosses the axis of the base cylinder at the fixed angle p and the points a-b-c-d constitute starting points of identical frontal involutes a-a', b-b', c-c', and d-d' of the tooth flank 3. The frontal involute bb' is constructed in such a manner that its starting point coincides with the lowest point of a line 5 which represents the contact line between the grinding disk (not shown in Pig. 1) and the tooth flank. The top point c' of contact line 5 lies on the involute c-c'.

Fig. 2 shows a tooth identical with that shown in Fig. l, wherein a truing tool of a blade or edged type 6, having the edge 6', coinciding with the generating line 4. The length of edge 6' is somewhat greater than the distance b-c' between the involutes b-b' and c-c', as measured along the generating line 4.

Fig. 3 shows a tooth identical to that shown in Fig. l and a single diamond point 8 reciprocally mounted in a guide arrangement 7. The traverse of the tool, as indicated by the arrow 9, is somewhat greater than the distance 12'-c' between the involutes b--b' and c-c', as measured along the generating line 4.

Fig. 4 is illustrative of a practical construction for moving an edged tool 6 having the edge 6', as hereinabove described. The tool is fastened by means of Screws 11 on a plate 12 in such a manner that edge 6' is at all times maintained tangent to the surface of a fixed areuate guide 1 of cylindrical shape identical with the base cylinder of a helical spur gear to be ground, '-as shown in Figs. 1-3. Th angle ;3 is formed between a line 2' parallel to the axis 2 of the cylinder 1 and the edge 6' of the tool which edge coincides with the tooth-generating line. The motion thus afforded for the edge 6' is such as to scan the surface intermediate the involute lines bb' and c-' of the tooth flank, as shown' in Figsfl 'and 2, cutting the material of the grinding wheel along thecontact line 5.

Fig. 5 illustrates a mechanical arrangement for moving a truing tool, for example, a diamond point 8, carried in slide bearings 7, which bearings are fixed to a plate 12, which will be understood to be rollable around the cylinder 1. Rolling bands 19 and 19 of conventional nature are utilized as shown in Figs. 4 and 5, to effect the rolling motion. A cam 13 is provided, Which may be power driven and disposed in a slot 14', cut into a reciprocal element 14. Thus, upon rotation of the cam it wouldjbe' apparent that the diamond point 8 Will likewise reciprocate, the arrangement being such that reciprocati'onis" along the generating line. 'Accordingly, by virtue of the reciprocal motion of the diamond point and a rolling' motion of plate 12 on the surface of cylinder 1, the diamond point 8 describes a zig-zag line 15 which sweeps back and forth across the contact line 5.

Fig. 6 illustrates the plan view of a machine for a pair of truing diamonds 8, Which serve for dressing the two working planes 10' and 10" of the grinding'disk 10. Each diamond is movably mounted in a socket head 16, being reciprocal in the direction of the arrows shown, that 'is, along the respective axes 17. The heads 16 are each fixed to a respective supporting bracket arm 18. The plates 12 and 12' are mounted so that they can ride, by means of rolling bands 19 and 19 on the same cylinder 1 as shown in Figs. 4 and 5. In Fig. 7 the bands are designated generally as 19. The plates interlock with protruding lugs 20. The ends of the rolling bands 19 are attached to the lugs 20. A bearing 21 is provided for the grinding disk shaft 22 which is swiveled on the frame of the machine and is vertically adjustable by suitable' means (not shown);

Fig. 7, showing the elevation of the device shown in Fig. 6, illustrates the manner in which the arms 18 are underslung and attached to the plates 12 and 12'. The axes 17 Whichguide the motion of their respective diamonds, reciprocally, are" located in the plane of the triangle 4-4'-4", as shown in Fig. l, and are, therefore, in a plane with the line of rolling contact between the plates and the cylinder 1. Each diamond may have its own operating motor (not shown) for etfcting reciprocation, which motors may be carried on the arms 18 or inside the heads 1 6. The heads 16 are carried on their supporting arms so as to be rotatively adjustable by any suitable means (not shown) for effecting the angle p in relation to the axis of the cylinder. Alternatively, edged tools, such as 6 as shown in Fig. 4, may be utilized in this arrangement.

Fig. 3 illustrates the installation of a dressing tool device as described in conjunction with Figs. 6 and 7 on a table 23 of a grinding machine having a head stock 24. A gear body workpiece 25 is carried between the head stock and a tail stock, as shown, on a suitable mandrel. The plates 12 and 12' are disposed so that they can arcuately roll around the cylinder 1 carried by table 23. Two diamonds 8 in diamond holders 26 '(one of which is illustrated) for truing both Working surfaces of a grinding wheel 10 are provided, carried'in heads 16 (not shown) as described in conjunction with Figs. 6 and 7. The dressing of the grinding disk is carried out by swiveling the plates whereby the two diamond holders are simultaneously moved back and forth. After completion of *the truing operation, table 23 is shifted .to the right so as to bring the workpiece 25 Underneath the grinding disk 10, whereupon a tooth on the workpiece may be ground.

A somewhat modified arrangement of the dressing tool is shown in Fig; 8a wherein the tool is` mounted above .the grinding disk 10a. ment comprising a roller 27 and slide bearing 28 is provided for guiding the roller la, equivalentttothe roller 1, in conjunction, with the template 12a and. diamond holder 26a. Thus, the integral mechanism 1a- -12a,-26a may be moved up and. down'by means efa cable passing over the roller 27. As the grinding disk 10a wears down the distance A between the axis of the grinding disk and .the axis of the workpiece changes. Accordingly, the dressing device is moved downwardly to cornpensate, that is, until the distance between the axis of the element 12a and the grinding disk axis equals the distance A.

The device described herein may be provided with interehangeable cylinders for use in conjunction with gears ofdiiferent base circles, it being understood, referring to Fig. 1, that the radius r of the cylinder 1 is at all times equal to the radius of the base circle of the gear to be ground. Also, devices can be constructed having 'adjustable base circle radii so that a single machine may grind gears of a large variety of base circles.

Having thus described my invention, I am aware that various changes may be made without departing from the spirit thereof and, accordingly, I do not seek to be limited to the precise illustration herein given except as set forth in the appended claims.

I claim:

l. In a machine for profiling grinding disks to be used in grinding :the fianks of helical spur gear teeth having a predetermined base circle; a dressing tool mount for holding a dressing tool and means for efleeting reciprocal straight line motion of said mount, means for rollably moving said mount on a circular surface having a radius equal to the radius of said base circle 'with a rolling' motion relative the' axis of said. circle' the'lie of ,r'eciprocation of said, mount effetin'g a, constant, predetermined 'angle withfa' line "parallel to theaxis of said.

surface ahdlying on saidsurface.

2. A machine of the class described, amount for a dressing tool and means for reciprocating saidmount in a straight line, a guide element having acylindrieal surface and means efiecting a rolling motion of said mount on said surface, wherein said straight line reciprocation A suitable 'suspension arrange# is on a line making a constant angle [3g with an element` of said cylindrical surface.

3. In`a machine as set'fo'rth in claim 2, including a base for said machine for holding a`cylindrica1 workpiece and for holding said guideelement, wherein the axes of said workpiece and said guide element are parallel.

4. In a machine'for profiling grinding disks to be used in grinding .theflanks of helicalspur gear .teeth having a predetermined base circle; a dressing tool mount for holding a dressing tool and means for eifecting reciprocal *straight line motion 'of said mount,` 'means for moving sliding motion, said tool holding element having a slot,

and cam means rotative in said slot and engrging the sides thereof to effect reciprocation of said tool holding element.

5. In a machine for grinding helicoidal spur gear teeth; a slidable base, a mount for a dressing tool to dress the face 'of a grinding disk, guide means for efiecting a rolling motion of said mount around a fixed axis so that arcuate travel of said mount defines' a cylindrical surface, said guide means and said mount being carried by said slidable base, support means carried by 'said base for supporting a spur gear body workpiece of cylindrical configuration with the axis thereof parallel to the axis of rolling movement of said mount, whereby said slidable base may be moved to bring' said workpiece or said dressing tool carried by said mount into engagement with said grinding disk.

6. A device for dressing a profile grinding disk for grinding helical single spur gear teeth, comprising a mount for a dressing tool, means comprising a dressing tool carried by said mount and disposed for cutting at a fixed angle p on a tooth generating line with respect to said mount and along a curvilinear path with respect to a grinding disk, said curvilinear path being efiected by plate control means for effecting tangential rolling of said mount around a fixed axis at a fixed distance therefrom, said tooth generating line making a constant angle with a line constituting an element of a cylindrical surface of revolution generated by rolling of said mount about said fixed axis, the radius of said cylindrical surface being equal to the base circle of the gear teeth intended to be ground by said disk.

7. A device as set forth in claim 6, said dressing tool comprising a straight edged cutter, the edge thereof being disposed on said tooth generating line.

8. A device as set forth in claim 6, said dressing tool comprising a pointed cutter, `a means for eflecting reciprocation of said cutter on said tooth generating line.

9. A device as set forth in claim 6, said plate control means comprising a cylindrical grinding element, said mount comprising a plate rollable around said cylindrical element and having an extending arm, and a tool holder at the free end of said arm.

10. In a device as set forth in claim 9, including an r additional plate and an additional arm thereon, and an additional cylindrical element for guiding said additional plate, said additional arm having a tool holder at the free end thereof, said tool' holders being spaced from each other so as to effect tool engagement with respective sides of a grinding disk.

11. In a machine for profiling grinding disks to be used in grinding the' flanks of helical spur gear teeth having a predetermined base circle; a dressing tool mount for holding a dressing tool disposed for cutting along a straight line for generating a tooth and means for moving said mount in a circular are having a radius equal to the radius of said base circlewith a rolling motion relative the axis of said circle, the working line of said dressing 6 tool effecting a constant, predetermined angle with a line parallel to the axis of said are and spaced therefrom at a distance equal to the radius of said are.

ing 'a predetermined base circle; a dressing tool mount for holding a dressing tool and means for effecting reciprocal motion of said mount along a straight line for generating a tooth, means for movingsaid mount in a cireular are having a 'radius equal to 'the radius of said base circle with 'a rolling motion relative the axis of-said circle, the' predetermined angle with a line' 'parallel to" the axis of' said are and spaced therefrom at a distance equal to the radius of said arc.

13. A device for dressing -a profile grinding disk for grinding helical single spur gear teeth, comprising a mount for a cutting tool, means comprising a dressing tool carried by said mount and disposed for cutting at a fixed angle on a tooth generating line with respect to said mount and along a curvilinear path with respect to a grinding disk, said curvilinear path being eifected by template control means for effecting tangential rolling of said mount around a fixed axis at a fixed distance therefrom, said tooth generating line making a constant angle with a line constituting an element of a cylindrical surface of revolution generated by rolling of said mount about said fixed axis, the radius of said cylindrical surface being equal to the base circle of the gear teeth intended to be ground by said disk, said template control means comprising a cylindrical element, said mount comprising a plate rollable around said cylindrical element and having an extending arm, anda tool holder at the free end of said arm, said tool holder being pivotally adjustable to effect 'a selected angle for said tooth generating line.

14. In a grinding machine, a device for profiling grinding disks to be used in grinding the flanks of helical spur gear teeth having a predetermined base circle, said device comprising a mount for holding a dressing tool disposed for cutting along straight lines for generating a tooth flank and means for rollably moving said mount comprising a cylindrical member on the surface of which said mount rolls, sai-d cylindrical member having a radius equal to the radius of said base circle, means whereby said cylindrical member is fixed to said grinding machine, wherein the cutting line of said dressing tool effects a constant predetermined angle with a line parallel to the v axis of said cylindrical member and lying on the surface thereof. v

15. In a machine for profiling grinding disks to be used in grinding the flanks of helical spur gear teeth having a predetermined base circle, a dressing tool mount for holding a dressing tool disposed for cutting along a straight line for generating 'a tooth and means for rollably moving said mount on a cylindrical rolling are parallel to the axis of same, said rolling are having a radius equal to the radius of said base circle, the other line of said dressing tool effecting a constant, predetermined angle with a line parallel to the axis 'of said are surface, and lying on said arc surface.

16. A machine of the class described, `a mount for a 'dressing tool and means `for reciprocating said mount in a straight line, a guide element having'a cylindrical surface and means elfecting a rolling motion of said mount on said surface, wherein said straight line reciprocation means for effeoting vertical slidability and guidance thereof, said bearing means being fixed relatively immovable with respect to said machine.

' 17. In a machine for grinding helicoidal' spur gear slidable base may be moved to bring said workpiece or teeth; a slidable base, a mount for a dressing' tool to said dressing tool carried b y said mount into engage dress the faceof a grinding disk, guide means for effectment with said grinding disk, ing a' rolling motion of said' mount on the' surface of said gilide means parallel to the axis of same so that rolling 5 References cited in the file Of his pa en travel of the dressing line ofsaid dressing tool envelopes UNITED STATES PATENTS,

a hehcoldal u su c s ml ns mg 1937961 Hutchinson &05,1933

carried by said slidable base and said mount being carried by said guide means, jsn p'ort' niean slarried .by saidbase Aepph May 1945 for supporting a spur 'gear, body workp iece ofcylindrical 10 configuration with the' akis thereof parallel to the axis FOREIFHTI PATENTS of the rolling movement of said mount, whereby said 5 211 Great Bmam 1939 

